Method for early detection of cooling-loss events

ABSTRACT

A method of detecting cooling-loss event early is provided. The method includes defining a relative humidity limit and change threshold for a given space, measuring relative humidity in the given space, determining, with a processing unit, whether the measured relative humidity is within the defined relative humidity limit, generating a warning in an event the measured relative humidity is outside the defined relative humidity limit and determining whether a change in the measured relative humidity is less than the defined change threshold for the given space and generating an alarm in an event the change is greater than the defined change threshold.

This invention was made with Government support under Contract No.:DEEE0002897 awarded by Department of Energy. The Government has certainrights in this invention.

BACKGROUND

The present invention relates to a method and system for early detectionof cooling-loss events.

In instrumented buildings, such as data centers that house multiplecomputing devices, temperature sensors monitor the air temperature inthe enclosed space where the computing devices are held. Generally, thealarm systems of such buildings are based only on temperature readingsof those temperature sensors. A problem with this approach is thattemperature sensors typically have large thermal constants due to thefact that they often have a strong thermal coupling to the thermal massof their housing. This leads to the temperature sensors havingcharacteristically slow response times to changes in air temperature.Thus, the alarm systems, which are based on the temperature readings ofthe temperature sensors, may also be characteristically slow toinitiate.

The resulting delay between a temperature increase in the buildings andthe initiation of the alarm systems can be relatively long and may leadto damage to delicate or temperature sensitive tools, such asinformation technology (IT) equipment.

SUMMARY

According to one embodiment of the present invention, a method ofdetecting cooling-loss events is provided. The method includes defininga relative humidity limit and change threshold for a given space,measuring relative humidity in the given space, determining, with aprocessing unit, whether the measured relative humidity is within thedefined relative humidity limit, generating a warning in an event themeasured relative humidity is outside the defined relative humiditylimit and determining whether a change in the measured relative humidityis less than the defined change threshold for the given space andgenerating an alarm in an event the change is greater than the definedchange threshold.

According to another embodiment, a method of detecting cooling-lossevents is provided. The method includes defining relative humidity andtemperature limits and change thresholds for a given space, measuringrelative humidity and temperature in the given space, determining, witha processing unit, whether either of the measured relative humidity andtemperature is within the defined relative humidity and temperaturelimits and generating a warning in an event either the measured relativehumidity or temperature is outside the defined relative humidity andtemperature limits and determining whether a change in the measuredrelative humidity is less than the defined change threshold for thegiven space and generating an alarm in an event the change is greaterthan the defined change threshold.

According to yet another embodiment, a system for early detection of acooling-loss event is provided and includes an enclosure to define agiven space in which multiple temperature sensitive devices are stored,a relative humidity sensor operably disposed in the given space and anearly detection apparatus including an alarm system disposed in signalcommunication with the relative humidity sensor. The early detectionapparatus is configured to initiate the alarm system to generate analarm in accordance with the relative humidity sensor sensing that achange in a relative humidity in the given space exceeds a definedchange threshold for the given space.

Additional features and advantages are realized through the techniquesof the present invention. Other embodiments and aspects of the inventionare described in detail herein and are considered a part of the claimedinvention. For a better understanding of the invention with theadvantages and the features, refer to the description and to thedrawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The subject matter which is regarded as the invention is particularlypointed out and distinctly claimed in the claims at the conclusion ofthe specification. The forgoing and other features, and advantages ofthe invention are apparent from the following detailed description takenin conjunction with the accompanying drawings in which:

FIG. 1 is a schematic diagram illustrating a system for early detectionof a cooling-loss event;

FIG. 2 is a flow diagram illustrating a method of early detection ofcooling-loss events in accordance with embodiments;

FIG. 3 is a graphical depiction of a response time of a relativehumidity sensor; and

FIG. 4 is a graphical depiction of relative humidity and temperaturereadings versus timing.

DETAILED DESCRIPTION

The description provided below relates to the use of measurements ofrelative humidity (RH) sensors to promptly detect critical eventsinvolving the loss of cooling capacity in buildings like data centers.The use of the RH measurements may be based on RH and temperature (T)sensor trends and measurements and can also incorporate, if available,pressure (P) sensor measurement for verifying proper air conditioningequipment functioning, air flow, etc.

With reference to FIG. 1, a system 10 is provided for early detection ofa cooling loss event. The system 10 includes an enclosure 20, one ormore relative humidity sensors 30 and an early detection apparatus 40.The enclosure 20 may be provided as a building or room that is formed todefine a given space 21 in which multiple temperature sensitive devices22 are stored. The temperature sensitive devices 22 may includecomputing or information technology (IT) devices. The one or morerelative humidity sensors 30 are operably disposed in the given space 21to detect relative humidity in the given space 21. To this end, the oneor more relative humidity sensors 30 may include a capacitive transducer31 or a similar device.

In any case, the one or more relative humidity sensors 30 do not presentthermal constants and notice immediate (or substantially immediate)changes in relative humidity conditions in the given space 21. Thus,since relative humidity in the given space 21 is proportional to airtemperature in the given space 21, the one or more relative humiditysensors 30 can be relied upon to sense immediate changes in bothrelative humidity and air temperature in the given space 21 such that afailure of a cooling system (i.e., an instance of a cooling-loss event)can be inferred relatively quickly. Depending on its active material,the humidity sensor response characteristics may vary depending ondifferent parameters, like capacitance, resistance or conductivity.

The system 10 may further include one or more pressure sensors 32 andone or more temperature sensors 33 in the given space 21. The pressuresensors 32 can be employed to verify that the air conditioning units insystem 10 have their fans operating correctly. The one or moretemperature sensors 33 can be used to determine air temperature in thegiven space 21 as well as a change in the air temperature but will tendto react more slowly than the one or more relative humidity sensors 30due to their relatively large thermal constants.

The early detection apparatus 40 may include a processing unit 41 and acomputer readable medium 42, such as a memory or data storage unit. Thecomputer readable medium 42 has executable instructions stored thereon.When executed, the executable instructions cause the processing unit 41to operate as described below. In particular, the processing unit 41 mayinclude a warning system 410 and an alarm system 411. The warning system410 is disposed in signal communication with at least the one or morerelative humidity sensors 30 and the one or more temperature sensors 33.The alarm system 411 is disposed in signal communication with at leastthe one or more relative humidity sensors 30.

The executable instructions of the computer readable medium 42 of theearly detection apparatus 40 are provided such that the processing unit41 of the early detection apparatus 40 is configured to operate inaccordance with at least the exemplary method illustrated in FIG. 2. Asshown in FIG. 2, the processing unit 41 defines initial operationalparameters of relative humidity (RH₀) and air temperature (T₀) for thegiven space 21 in operation 200. In accordance with embodiments, theinitial operational parameters of relative humidity (RH₀) may be abaseline relative humidity, high and low relative humidity limits and arelative humidity change threshold within a certain period. Similarly,in accordance with embodiments, the initial operational parameters ofair temperature (T₀) may be a baseline air temperature, high and low airtemperature limits and an air temperature change threshold.

Once the initial operational parameters of relative humidity (RH₀) andtemperature (T₀) for the given space 21 are defined, the processing unit41 causes the one or more relative humidity sensors 30 and the one ormore temperature sensors 33 to measure the relative humidity and airtemperature in the given space 21 in operation 210. The processing unit41 then interrogates the one or more relative humidity sensors 30 andthe one or more temperature sensors 33 for their respective readings anddetermines, in operation 220, whether the relative humidity and airtemperature of the given space 21 is within the limits defined inoperation 200.

In an event that the relative humidity and air temperature of the givenspace 21 is within the limits defined in operation 200, the processingunit 41 updates historical trends in operation 230 and returns controlto operation 200. In operation 200, the historical trends are consideredin the definition of the initial operational parameters. In an eventthat one of the relative humidity and air temperature of the given space21 is not within the limits defined in operation 200, the processingunit 41 initiates the warning system 410 to generate a warning thatthere may be a current risk of a cooling-loss event in operation 240.

Once the warning is generated, in operation 250, the processing unit 41determines whether a change in the relative humidity of the given space21 exceeds the relative humidity change threshold defined in operation200. In an event that the relative humidity of the given space 21 doesnot exceed the relative humidity change threshold defined in operation200, the processing unit 41 updates historical trends in operation 230and returns control to operation 200. In an event that the relativehumidity of the given space 21 exceeds the relative humidity changethreshold defined in operation 200, the processing unit 41 initiates thealarm system 411 to generate an alarm that there is a cooling-loss eventin operation 260 and returns control to operation 200.

With reference to FIGS. 3 and 4, the advantages of using the one or morerelative humidity sensors 30 can be seen. As described above, relativehumidity is a unit-less parameter that describes an amount of watervapor in the air of the given space 21 and directly depends on the airtemperature. FIG. 3 is a graphical depiction of a typical response of arelative humidity sensor to changes in relative humidity and illustratesthat the response time can be measured in seconds. By contrast, withreference to the graphical depiction of relative humidity andtemperature readings versus timing in FIG. 4, it can be seen that anincrease in a relative humidity of an 80,000 square foot data centerthat loses cooling capacity precedes the corresponding increase in airtemperature by several minutes. As to the disclosure of FIG. 4, arelevant metric is the change in RH, not its absolute value. Forexample, if water vapor in air is not being extracted during a coolingloss event, everything else being the same, the RH level can increaseeven if the temperature increases, until equilibrium is reached.

Thus, from the fast response time illustrated in the graph of FIG. 3, itcan be inferred that the relative humidity increase will be observed andreacted to by the early detection apparatus 40 due to its reliance uponthe one or more relative humidity sensors well before the temperatureincrease and certainly before a detection apparatus relying only ontemperature sensors would be able to react.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of onemore other features, integers, steps, operations, element components,and/or groups thereof.

The corresponding structures, materials, acts, and equivalents of allmeans or step plus function elements in the claims below are intended toinclude any structure, material, or act for performing the function incombination with other claimed elements as specifically claimed. Thedescription of the present invention has been presented for purposes ofillustration and description, but is not intended to be exhaustive orlimited to the invention in the form disclosed. Many modifications andvariations will be apparent to those of ordinary skill in the artwithout departing from the scope and spirit of the invention. Theembodiments were chosen and described in order to best explain theprinciples of the invention and the practical application, and to enableothers of ordinary skill in the art to understand the invention forvarious embodiments with various modifications as are suited to theparticular use contemplated.

The flow diagrams depicted herein are just one example. There may bemany variations to this diagram or the steps (or operations) describedtherein without departing from the spirit of the invention. Forinstance, the steps may be performed in a differing order or steps maybe added, deleted or modified. All of these variations are considered apart of the claimed invention.

While the preferred embodiment to the invention had been described, itwill be understood that those skilled in the art, both now and in thefuture, may make various improvements and enhancements which fall withinthe scope of the claims which follow. These claims should be construedto maintain the proper protection for the invention first described.

What is claimed is:
 1. A method of detecting cooling-loss events,comprising: defining a relative humidity limit and change threshold fora given space; measuring relative humidity in the given space;determining, with a processing unit, whether the measured relativehumidity is within the defined relative humidity limit; generating awarning in an event the measured relative humidity is outside thedefined relative humidity limit; and determining whether a change in themeasured relative humidity is less than the defined change threshold forthe given space and generating an alarm in an event the change isgreater than the defined change threshold.
 2. The method according toclaim 1, further comprising repeating the measuring subsequent to thegenerating of the alarm.
 3. The method according to claim 1, wherein thedefining of the relative humidity limit is in accordance with historicaltrends.
 4. The method according to claim 3, further comprising updatingthe historical trends in an event the measured relative humidity iswithin the defined relative humidity limit.
 5. A method of detectingcooling-loss events, comprising: defining relative humidity andtemperature limits and change thresholds for a given space; measuringrelative humidity and temperature in the given space; determining, witha processing unit, whether either of the measured relative humidity andtemperature is within the defined relative humidity and temperaturelimits and generating a warning in an event either the measured relativehumidity or temperature is outside the defined relative humidity andtemperature limits; and determining whether a change in the measuredrelative humidity is less than the defined change threshold for thegiven space and generating an alarm in an event the change is greaterthan the defined change threshold.
 6. The method according to claim 5,further comprising repeating the measuring subsequent to the generatingof the alarm.
 7. The method according to claim 5, wherein the definingof the relative humidity and temperature limits is in accordance withhistorical trends.
 8. The method according to claim 7, furthercomprising updating the historical trends in an event the measuredrelative humidity or temperature is within the defined relative humidityand temperature limits.
 9. A system for early detection of acooling-loss event, the system comprising: an enclosure to define agiven space in which multiple temperature sensitive devices are stored;a relative humidity sensor operably disposed in the given space; and anearly detection apparatus including an alarm system disposed in signalcommunication with the relative humidity sensor, the early detectionapparatus being configured to initiate the alarm system to generate analarm in accordance with the relative humidity sensor sensing that achange in a relative humidity in the given space exceeds a definedchange threshold for the given space.
 10. The system according to claim9, wherein the multiple temperature sensitive devices comprise computingdevices.
 11. The system according to claim 9, wherein the multipletemperature sensitive devices comprise information technology (IT)devices.
 12. The system according to claim 9, wherein the relativehumidity sensor comprises a capacitive transducer.
 13. The systemaccording to claim 9, further comprising a pressure sensor to verify areading of the relative humidity sensor.
 14. The system according toclaim 9, wherein the early detection apparatus comprises a warningsystem and is configured to generate a warning in an event the relativehumidity sensor senses that relative humidity in the given space isoutside a defined relative humidity limit.
 15. The system according toclaim 9, wherein the early detection apparatus comprises: a processingunit; and a computer readable medium having executable instructionsstored thereon, which, when executed, cause the processing unit todetermine that the relative humidity sensor senses that a change in arelative humidity in the given space exceeds a defined change thresholdfor the given space and to initiate the alarm system to generate thealarm accordingly.
 16. The system according to claim 15, wherein, whenexecuted, the executable instructions further cause the processing unitto define the change threshold for the given space and to update thedefined change threshold for the given space in certain circumstances.17. The system according to claim 9, further comprising a temperaturesensor to sense a temperature of the given space.
 18. The systemaccording to claim 17, wherein the early detection apparatus comprises awarning system and is configured to generate a warning in an event therelative humidity sensor senses that relative humidity in the givenspace is outside a defined relative humidity limit or the temperaturesensor senses that a temperature of the given space is outside a definedtemperature limit.
 19. The system according to claim 17, wherein theearly detection apparatus comprises: a processing unit; and a computerreadable medium having executable instructions stored thereon, which,when executed, cause the processing unit to determine that the relativehumidity sensor senses that a change in a relative humidity in the givenspace exceeds a defined change threshold for the given space and toinitiate the alarm system to generate the alarm accordingly.
 20. Thesystem according to claim 19, wherein, when executed, the executableinstructions further cause the processing unit to define the changethreshold, the defined relative humidity limit and the definedtemperature limit for the given space and to update the defined changethreshold, the defined relative humidity limit and the definedtemperature limit for the given space in certain circumstances.